Impact device

ABSTRACT

Described herein is an impact device that may be slidably coupled to a wire rope barrier terminal end and, in the event of an impact on or about the terminal end by a vehicle, the impact device is configured to slide or advance along the terminal end wire rope(s) towards a wire rope barrier end and away from a terminal end anchor position. In a further embodiment, a method is described of retrofitting existing wire-rope barrier terminal ends with the device. The impact device may simultaneously (at least to some extent) absorb kinetic energy from the impact as well as redirect the direction of impact along the terminal end wire rope(s) towards, and optionally along, the wire rope barrier itself depending on the extent of impact. The sliding action also knocks over any posts in the direction of errant vehicle travel in an impact.

BACKGROUND OF THE INVENTION

This application derives priority from New Zealand patent application number 761715 dated 13 Feb. 2020 with WIPO DAS code 9634 incorporated herein by reference.

Described herein is an impact device. More specifically an impact device, a wire rope barrier terminal end, and a wire rope barrier are described along with associated methods of use and action.

Wire rope barriers (also termed cable barriers) are widely used for vehicle management alongside roadways, bridges and so on. These barriers aim to prevent a vehicle from diverting from a lane or roadway and redirect the errant vehicle back along the roadway and away from hazards such as on-coming traffic, trees or other barriers.

The basic design of a wire rope barrier is to provide elongated runs of wire (usually two to three wire ropes), the wire ropes located generally parallel to a roadway and held above the road surface via a series of posts. In the event of an impact, the post(s) fall away and allow the wire rope(s) to absorb the vehicle kinetic energy and cause deceleration and vehicle re-direction.

Wire rope barriers comprise ends, termed hereafter as terminal ends. Terminal ends must hold and retain tension in the wire ropes usually by anchoring the separate wire ropes to an anchor such as a restraint on a road surface. Terminal ends often are designed to act to gather together and direct wire ropes towards a common anchor point.

Important in terminal end design is the need to cater for the scenario of a vehicle striking the terminal end and how to minimise or avoid injury to the vehicle driver when this occurs. One aspect of minimising harm is to have the terminal end absorb at least some of the energy of the collision to decelerate the vehicle. A further challenge of terminal end and wire rope barrier design is to avoid the vehicle becoming airborne as can happen for example if wire ropes or posts do not knock over or drop beneath the vehicle as a vehicle strikes a terminal end.

As may be appreciated from the above, wire rope barrier designs pose several challenges, such as:

-   -   designing a wire rope barrier and terminal ends that hold and         restrain wire ropes under tension over time;     -   designing a terminal end that minimises or avoids injury to a         vehicle driver in the event of an impact on the terminal end;     -   designing a terminal end that does not influence the restraint         action of a wire rope barrier in the event of a vehicle impact         on the wire rope.

Another design aspect may be that of providing a device that supports or assists with meeting the above design challenges and which is able to be used in new wire rope barriers and able to be retrofitted to existing wire rope barriers already in service.

Further, one drawback of many existing art wire rope barrier systems is that their terminal ends are comparatively long in physical dimensions. The greater length needed may sometimes limit where such barriers may be used and/or limit the length of need (LON) section of the barriers.

It is acknowledged that sliding devices exist in the context of guard rails or W-beam and their beam barriers, however, wire rope barriers present unique design problems to guard rail barriers. For example, each rope in a wire rope barrier reacts individually to an imposed force unlike a solid and rigidly formed W-beam. Further, a wire rope has minimal if any shape retaining effects when placed in compression along the longitudinal length of a wire rope. By contrast, a guard rail barrier is formed as a single or modular unit with at least some inherent rigidity even when placed in compression. Art in respect of guard rails usually focus on deformation techniques of an impact part and/or crushing techniques to flatten or otherwise deform the guard rail shape. Crushing and deformation techniques do not inherently translate to wire rope arrangements.

As may be appreciated from the above, it may be useful to provide a wire rope terminal end with a device that helps to reduce/avoid driver injury. Reduction may be through enhanced barrier collapse dynamics in the event of an impact to the terminal end. Amendment of existing terminal ends with minimal cost may be useful too especially given the considerable infrastructure already in place and the considerable value and importance placed on increased driving safety. A further advantage may be to provide a design that allows for shorter terminal ends and therefore reduce the barrier footprint and potentially redirect errant vehicles at a point closer to the terminal end section of a wire rope barrier.

Further aspects and advantages of the impact device, a wire rope barrier terminal end, and a wire rope barrier will become apparent from the ensuing description that is given by way of example only.

SUMMARY OF THE INVENTION

Described herein is an impact device that may be slidably coupled to a wire rope barrier terminal end and, in the event of an impact on or about the terminal end by a vehicle, the impact device is configured to slide or advance along the terminal end wire rope(s) towards a wire rope barrier end and away from a terminal end anchor position. In a further embodiment, a method is described of retrofitting existing wire-rope barrier terminal ends with the device. The impact device may simultaneously (at least to some extent) absorb kinetic energy from the impact as well as redirect the direction of impact along the terminal end wire rope(s) towards, and optionally along, the wire rope barrier itself depending on the extent of impact. The sliding action also knocks over posts in the direction of errant vehicle travel in an impact when the impact is end on or about the terminal end and towards to wire rope barrier. The sliding action also acts to gather together and direct wire rope movement during an impact.

In a first aspect, there is provided an impact device comprising:

-   -   a contact element configured to contact and optionally engage an         errant vehicle in a collision event,     -   a guide member configured to receive and retain at least one         barrier wire rope about or therein, and,     -   in the event of an impact, the impact device slidingly engages         the at least one barrier wire rope about or therein the guide         member and wherein the at least one wire rope is directed about         or through the contact element during sliding of the impact         device along the at least one barrier wire rope.

In a second aspect, there is provided a terminal end comprising:

-   -   at least one wire rope, at least one post and at least one         anchor point for the at least one wire rope, the terminal end         configured to gather and direct at least one wire rope from a         barrier position with the wire rope elevated above a ground         surface to an anchored position about or on the ground; and     -   an impact device substantially as described above.

In a third aspect, there is provided a wire rope barrier comprising wire rope, terminal ends and at least one impact device, wherein:

-   -   the wire rope barrier comprises at least one wire rope the wire         ropes located generally parallel to a roadway and held above the         road surface via a series of posts;     -   the terminal ends comprising at least one wire rope, at least         one post and at least one anchor point for the at least one wire         rope, the terminal end configured to gather and direct at least         one wire rope from a barrier position with the wire rope         elevated above a ground surface to an anchored position about or         on the ground; and     -   mounted on or about one or both terminal ends, at least one         impact device substantially as described above.

In a fourth aspect, there is provided a method of absorbing and directing the energy associated with an impact on or about a wire rope barrier terminal end by a vehicle, the method comprising the steps of:

-   -   providing a wire rope barrier substantially as described above;         and     -   in the event of an impact by a vehicle to the wire rope barrier         terminal end, the impact in turn being at least partly received         by the impact device and, on impact the impact device sliding         along the at least one wire rope.

In a fifth aspect, there is provided a method of removing wire rope barrier posts in the event of an impact on a wire rope barrier terminal end by a vehicle, the method comprising the steps of:

-   -   providing a wire rope barrier substantially as described above;         and,     -   in the event of an impact by a vehicle to the wire rope barrier         terminal end, the impact in turn being at least partly received         by the impact device and, on impact the impact device sliding         along the at least one wire rope, the action of sliding acting         to knock over the posts ahead of the vehicle direction of         travel.

As may be appreciated from the above, it may be useful to provide a wire rope terminal end with a device that helps to reduce/avoid driver injury. Reduction may be through enhanced barrier collapse dynamics in the event of an impact to the terminal end. Amendment of existing terminal ends with minimal cost may be useful too especially given the considerable infrastructure already in place and the considerable value and importance placed on increased driving safety.

A further advantage may be to provide a design that allows for shorter terminal ends and therefore reduce the barrier footprint and potentially redirect errant vehicles at a point closer to the terminal end section of a wire rope barrier.

More aspects and advantages of the above impact device, terminal end, barrier and associated methods and uses are described further below.

DESCRIPTION OF THE DRAWINGS

Further aspects of the impact device, a wire rope barrier terminal end, and a wire rope barrier will become apparent from the following description that is given by way of example only and with reference to the accompanying drawings in which:

FIG. 1 illustrates a plan view of one embodiment of an impact device;

FIG. 2 illustrates a detail plan view of area A in FIG. 1 showing the impact device about the head region;

FIG. 3 illustrates a side elevation of the impact device;

FIG. 4 illustrates a perspective view from in front and above the impact device;

FIG. 5 illustrates a further perspective view of the impact device from above and behind;

FIG. 6 illustrates a further perspective view of the impact device from above and behind;

FIG. 7 illustrates a side perspective view of the impact device assembled with a wire rope barrier and terminal end, the impact device also including rounded directing sides;

FIG. 8 illustrates a schematic plan view of an alternative embodiment of impact device used to increase the resistance to sliding movement of the impact device;

FIG. 9 illustrates a schematic perspective view of an alternative embodiment of impact device used to increase the resistance to sliding movement of the impact device;

FIG. 10 illustrates a schematic side view of an alternative shape of impact device and legs;

FIG. 11 illustrates a side detail view of an installed impact device about the transition from barrier section to terminal end and the channel of the impact device;

FIG. 12 illustrates a plan detail view of the installed impact device about the channel to head transition;

FIGS. 13 to 21 illustrate a series of side perspective views of the impact device, terminal end and barrier in the time period immediately prior to and at various moments post impact;

FIG. 22 illustrates a side view of an alternative impact device design with no opening in the face and wire rope cables passing below the face via a void in the guide member; and

FIGS. 23 and 24 illustrate a side and perspective view of an alternative embodiment of guide element in this example using a pair of brackets to connect the impact device to the barrier wire ropes; and

FIGS. 25 and 26 illustrate a side and perspective view of a further alternative embodiment of guide element, in this case with the brackets having a U-shape and connecting about the wire ropes.

DETAILED DESCRIPTION OF THE INVENTION

As noted above, an impact device is described that may be slidably coupled to a wire rope barrier terminal end and, in the event of an impact on or about the terminal end by a vehicle, the impact device is configured to slide or advance along the terminal end wire rope(s) towards a wire rope barrier end and away from a terminal end anchor position. In a further embodiment a method is described of retrofitting existing wire-rope barrier terminal ends with the device. The impact device may simultaneously (at least to some extent) absorb kinetic energy from the impact as well as redirect the direction of impact along the terminal end wire rope(s) towards, and optionally along, the wire rope barrier itself depending on the extent of impact. The sliding action also knocks over any posts in the direction of errant vehicle travel in an impact. The sliding action also acts to gather together and direct wire rope movement during an impact when the impact is end on or about the terminal end and towards to wire rope barrier.

For the purposes of this specification, the term ‘about’ or ‘approximately’ and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term ‘substantially’ or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term ‘comprise’ and grammatical variations thereof shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

Impact Device

In a first aspect, there is provided an impact device comprising:

-   -   a contact element configured to contact and optionally engage an         errant vehicle in a collision event,     -   a guide member configured to receive and retain at least one         barrier wire rope about or therein, and,     -   in the event of an impact, the impact device slidingly engages         the at least one barrier wire rope about or therein the guide         member and wherein the at least one wire rope is directed about         or through the contact element during sliding of the impact         device along the at least one barrier wire rope.

A Terminal End

In a second aspect, there is provided a terminal end comprising:

-   -   at least one wire rope, at least one post and at least one         anchor point for the at least one wire rope, the terminal end         configured to gather and direct at least one wire rope from a         barrier position with the wire rope elevated above a ground         surface to an anchored position about or on the ground; and     -   an impact device comprising a face, an opening in the face with         a passage through the opening leading to an elongated channel,         the impact device configured to slidingly engage at least one         barrier wire rope in the channel and the at least one wire rope         directed through the opening in the face.

A Wire Rope Barrier

In a third aspect, there is provided a wire rope barrier comprising wire rope, terminal ends and at least one impact device, wherein:

-   -   the wire rope barrier comprises at least one wire rope the wire         ropes located generally parallel to a roadway and held above the         road surface via a series of posts;     -   the terminal ends comprising at least one wire rope, at least         one post and at least one anchor point for the at least one wire         rope, the terminal end configured to gather and direct at least         one wire rope from a barrier position with the wire rope         elevated above a ground surface to an anchored position about or         on the ground; and     -   mounted on or about one or both terminal ends, the at least one         impact device comprising a face, an opening in the face with a         passage through the opening leading to an elongated channel, the         impact device configured to slidingly engage at least one         barrier wire rope in the channel and the at least one wire rope         directed through the opening in the face.

A Method of Energy Absorbing and Directing

In a fourth aspect, there is provided a method of absorbing and directing the energy associated with an impact on or about a wire rope barrier terminal end by a vehicle, the method comprising the steps of:

-   -   providing a wire rope barrier comprising wire rope, terminal         ends and at least one impact device, wherein:

the wire rope barrier comprises at least one wire rope the wire ropes located generally parallel to a roadway and held above the road surface via a series of posts;

-   -   the terminal ends comprising at least one wire rope, at least         one post and at least one anchor point for the at least one wire         rope, the terminal end configured to gather and direct at least         one wire rope from a barrier position with the wire rope         elevated above a ground surface to an anchored position about or         on the ground; and     -   mounted on or about one or both terminal ends, the at least one         impact device comprising a face, an opening in the face with a         passage through the opening leading to an elongated channel, the         impact device configured to slidingly engage at least one         barrier wire rope in the channel and the at least one wire rope         directed through the opening in the face; and     -   in the event of an impact by a vehicle to the wire rope barrier         terminal end, the impact in turn being at least partly received         by the impact device and, on impact the impact device sliding         along the at least one wire rope.

A Method of Wire Rope Barrier Post Removal

In a fifth aspect, there is provided a method of removing wire rope barrier posts in the event of an impact on a wire rope barrier terminal end by a vehicle, the method comprising the steps of:

-   -   providing a wire rope barrier comprising wire rope, terminal         ends and at least one impact device, wherein:

the wire rope barrier comprises at least one wire rope the wire ropes located generally parallel to a roadway and held above the road surface via a series of posts;

-   -   the terminal ends comprising at least one wire rope, at least         one post and at least one anchor point for the at least one wire         rope, the terminal end configured to gather and direct at least         one wire rope from a barrier position with the wire rope         elevated above a ground surface to an anchored position about or         on the ground; and     -   mounted on or about one or both terminal ends, the at least one         impact device comprising a face, an opening in the face with a         passage through the opening leading to an elongated channel, the         impact device configured to slidingly engage at least one         barrier wire rope in the channel and the at least one wire rope         directed through the opening in the face; and,     -   in the event of an impact by a vehicle to the wire rope barrier         terminal end, the impact in turn being at least partly received         by the impact device and, on impact the impact device sliding         along the at least one wire rope, the action of sliding acting         to knock over the posts ahead of the vehicle direction of         travel.

Barrier

The term ‘barrier’ and grammatical variations thereof as referred to herein refers to a wire rope or cable barrier comprising at least one wire rope, the wire ropes located generally parallel to a roadway and held above the road surface via a series of posts, a section of barrier ending about terminal ends, the terminal ends located at either end of the barrier.

Terminal End

The term ‘terminal end’ or ‘terminal portion’ and grammatical variations thereof refers to the end portion of a barrier. Typically, the terminal end commences about a final post, the wire ropes of the barrier sloping from a first vertical height equivalent to the rest of the barrier height to a second vertical height below the first vertical height, the second vertical height typically proximate the surface of the ground at an upstream side of the terminal end.

Terminal end wire ropes may be located so as to flare away from the longer wire rope barrier section. Flaring reaches a maximum extent about the upstream end of the terminal end. The flare may be substantially parabolic. The flare may be substantially linear. For these designs using flaring, the impact device may be located about the wire rope(s) at a point towards the downstream side of the terminal end nearer the first post of the barrier section and the wire ropes then flaring as they exit the impact device on the upstream side of the impact device.

In one embodiment, the wire rope(s) may be anchored at a terminal end in a non-releasing manner. That is, in the event of an impact on the impact device and subsequent additional tension force being applied to the wire rope(s) on account of the impact and subsequent sliding movement of the impact device, the wire rope(s) remain anchored in place. In an alternative embodiment, the wire rope(s) may be releasable and the anchor release the wire rope(s) in the event of an impact. Release may be at the moment or thereabouts of impact or at a time post the initial moment of impact.

Sliding

The term ‘sliding’ or grammatical variations thereof is used interchangeably with the term ‘advancing’ or grammatical variations thereof herein, referring to the impact device moving when impacted by an errant vehicle in a sliding manner relative to the wire rope(s) on which the impact device is mounted from an upstream position to a downstream position.

Upstream and Downstream

The terms ‘upstream’ and ‘downstream’ or grammatical variations thereof as used herein, refer to the relative positions of the wire rope relative to the impact device when engaged with a wire rope barrier or terminal end. The upstream end or side of the barrier or part thereof is where the impact device slides or advances from in a collision or impact and the downstream end or side of the barrier is where the impact device advances to in a collision. Typically, the upstream end is where the barrier wire rope cables may terminate and be coupled to a ground surface, this end usually facing on-coming vehicle traffic. The downstream side being the opposing portion of the terminal end facing towards the wire rope barrier itself and typically directed in parallel to the normal direction of travel of traffic on an adjoining roadway.

Energy Absorbing

As noted above, the impact device absorbs energy associated with an impact in turn at least to some extent, decelerating a vehicle and, at least to some extent, controlling the direction of the impact force and if needed, re-directing an impact force imposed on the impact device by an errant vehicle.

The action of sliding of the impact device may:

-   -   at least partly absorbing kinetic energy and     -   at least to some extent, redirecting the direction of impact         force to coincide with the direction of movement of the impact         device along the wire rope.

The way that energy is absorbed may be due to friction caused by the wire ropes moving about for face or through the impact device opening in the face and further, the channel, and this part or parts interfering with sliding movement of the impact device. The degree of friction imposed (and hence degree of energy absorbing) may be varied by amendment to the impact device design. For example, the path of movement of one or more wire ropes through the impact device may be straight, curved or tortuous. As may be appreciated, a straight path may present a lower degree of interference than a curved or tortuous path and hence a varied degree of friction resulting. Varied paths may be achieved using varied shaped channels or obstructions within a channel to impose a re-directing force on one or more wire ropes therein. The presence of obstructions may be used as well such as a narrowed opening or constriction in the sliding pathway to increase the extent of interference between the impact device and wire ropes (or a widened opening or chamber to decrease the extent of interference. Points at which the wire rope and impact device touch or move past each other may also be altered to change the coefficient of friction—this could be by material variation or by surface finish variation for example.

Mechanical Deformation of the Impact Device

The way that energy is absorbed may also be influenced via mechanical deformation of the impact device. Deformation may be elastic or plastic deformation. Deformation at least to some extent may occur at impact and/or during sliding movement thereafter of the impact device. As may appreciated, the extent of mechanical deformation may influence the extent of energy absorbing and hence this factor may be designed for to influence the impact device characteristics. By way of example, the degree of mechanical deformation and may be adjusted for through material choice, impact head shape and configuration, use of sacrificial materials or device forms or parts, use of crushing sections and so on. In one embodiment, the impact device or parts thereof may be manufactured from metals or metal alloys selected for their deformation characteristics and/or shaped to predetermine the deformation characteristics.

In one embodiment for example, the impact face may have directional strength during impacts depending on whether the impact is in a normal sliding forward direction and the vehicle impacts directly on the face, or in the reverse direction. In the forward direction, the face corners may be strong and therefore may resist buckling or bending of the impact face. This may allow the vehicle to be held in contact with the impact face during the period of the impact event. In the event of a reverse direction impact directly behind the impact face, the impact face and connecting members may comprise relatively weak areas, these weak areas bending or deforming thereby reducing the likelihood that the vehicle will rebound or be redirected off of the device and back into the road/traffic.

In a further embodiment, if a vehicle impacts the channel strut, the channel strut may be design to be relatively weak so that the strut(s) bend or deform. This approach may reduce the likelihood that the vehicle is redirected back into the traffic flow.

Both friction and mechanical deformation may be critical factors influencing the impact device characteristics and the extent of and way that the device absorbs and re-directs the energy caused by an impact on the impact device.

Deceleration and Redirection

As noted above, energy absorbing via the impact device dissipates kinetic energy, decelerates the impacting vehicle and re-directs the direction of impact force all to some extent.

Deceleration may be sufficient to bring the vehicle to a halt or reduce the vehicle speed below a predetermined speed. The degree of energy absorbing may be designed to achieve an optimum zone where deceleration occurs as quick as possible to minimise harm but not so fast as to cause injury to vehicle occupants noting that the human body has limits on G-forces able to be managed.

The rate of deceleration may be related to the speed of traffic travel on the adjoining road and likely mass of such vehicles. Because the impact device can advance along the wire rope barrier terminal end and onto and along the wire rope barrier itself, the rate of deceleration can be comparatively gradual so as to minimise risk of injury to the occupants and to maintain at least some degree of control over the vehicle speed and direction of movement during deceleration.

Knocking Over Posts

The impact device, once impacted by an errant vehicle may be pushed, via sliding action, downstream along the wire rope(s) and the impact device as it moves, deforms the barrier posts, clearing the posts out of the way during sliding movement. The impact device during sliding may impact the post(s) in their weak direction. The impact device, under impact and sliding, may also remove the cables from their post connection detail if present at the same time as knocking over the posts. This allows gating action.

One advantage of the impact device is that, as it advances along the wire rope barrier terminal end and after that the wire rope barrier itself, the way the impact device gathers and directs the wire ropes/forces the wire ropes to detach from the posts of the barrier and, as the impact device reaches the posts, the posts are free to knock over. Knocking over the posts reduces the overall height of the wire ropes above the ground and reduces or avoids any ramping effect of the wire ropes on a vehicle as the vehicle passes over the top of the cables and posts. Ramping is particularly dangerous as this causes a vehicle to become airborne and/or roll. Ideally a vehicle travels roughly inline or parallel to the wire rope longitudinal length and remains with all four wheels on the ground for maximum traction.

The term ‘knock over’ or grammatical variations thereof is used herein to represent a variety of forms of movement of a post such as flattening, falling sideways, pushing over, breaking off, lowering, bending and combinations of these forms of movement. Typically wire rope barrier posts are coupled to the ground at one end, perhaps into the soil or concrete, and are manufactured from steel or plastic shaped to deform when under impact. Essentially the term ‘knocking over’ has a similar result of the post moving beneath an errant vehicle at least to an extent that they do not become a collision hazard or ramp to vehicle advancement downstream along the barrier.

A further advantage of the design described is that tension in the wire rope barrier and the lower upstream terminal end connection point will tend to urge the wire ropes down towards ground level as posts are knocked over. This in turn acts to avoid an upward force on a vehicle thereby minimising risk of a ramping effect causing the vehicle to become airborne in a collision. Minimising risk of a vehicle becoming airborne is of importance in minimising passenger injury since, once airborne, the vehicle's movement is no longer controlled.

Protection of Length of Need (LON)

The impact device may protect an errant vehicle from impacting the Length of Need (LON) section of a wire rope barrier. When impacted the wire rope tension inherently reduces as the LON section conflates however, significant tension remains in the wire ropes or at least sufficient tension to help in energy absorbing during the terminal end impact and sliding movement of the impact device.

Direction of Impact

The impact device may be designed for a vehicle impacting the impact device approximately end-on i.e. approximately aligned with the wire rope barrier longitudinal length. The inventors have found that some variation to a purely end-on collision or impact may be catered for and collisions with vehicles striking the impact device at up to 1, or 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10, or 11, or 12, or 13, or 14, or 15, or 16, or 17, or 18, or 19, or 20, or 21, or 22, or 23, or 24, or 25, or 26, or 27, or 28, or 29, or 30 degrees off-set from an end-on zero degree angle may still cause advancement of the impact device and energy absorbing and redirection of the collision force at least to some extent in the advancement direction downstream along the longitudinal direction of the wire rope barrier.

Post Impact

After an impact on the wire rope barrier, the barrier parts may be fixed, replaced or re-positioned as necessary and the wire rope barrier re-commissioned. For example, after impact, any posts struck may be replaced and wire rope fitted to the new posts. The original (or a new) impact device may be fitted to the wire rope barrier terminal end.

Wire Rope Barrier

The wire rope barrier may be generally formed as per art installations using two to four wire ropes (also termed cables, the term rope(s) or cable(s) used interchangeably herein) extending longitudinally one above the other in a vertical plane. Posts spaced long the longitudinal axis of the barrier are fixed to the ground and used to restrain the wire ropes in place.

Contact Element

As noted above, the contact element may have the function of contacting and optionally engaging an errant vehicle in a collision event.

In one embodiment, the contact element may take the form of a face. The face may have a generally flat planar shape.

Hereafter, the terms ‘contact element’ and ‘face’ and grammatical variations thereof are used interchangeably and reference to a contact element does not exclude a face and reference to a face does not exclude the use of other forms of contact element with a similar function.

The face may in one embodiment be rectangular being at least approximately 5, or 6, or 7, or 8, or 9, or 10 times wider than a single wire rope diameter and at least 10, or 11, or 12, or 13, or 14, or 15, or 16, or 17, or 18, or 19, or 20 times taller than a single wire rope diameter.

The impact device face may have reinforcing flanges, fins, or struts extending from the face edge(s) to a point located along the channel longitudinal length. The use of flanges, fins or struts like this may be to assist with strength and stability of the impact face and/or transfer of impact energy to sliding movement of the impact device along the wire ropes.

Impact Plate

The impact device face may comprise an impact plate on the face for engaging an errant vehicle at or about the terminal end of the wire rope barrier. The impact plate may in one embodiment be sufficiently strong and/or hard to not deform when initially impacted. Alternatively, the impact plate may be designed to, at least to some extent, deform when struck and in doing so, absorb kinetic energy from the impact. In one embodiment, the face may be manufactured from steel, metal alloys and/or composite materials. Plastics may be used for some or all of the impact face, for example where a degree of plastic deformation is desirable under impact.

The face may in one embodiment comprise projections or other face features on a vehicle impact side that serve to engage with an errant vehicle or part thereof (e.g. the vehicle bumper, wheel, bodywork and so on) during an impact event.

Face Sides

The face of the impact device may optionally include sides extending from the impact plate configured to extend the impact region of the impact device.

In one embodiment, the impact plate sides may be rounded so that, when viewed from above, the face of the impact device has a semi-circular shape. In one embodiment, the sides may extend in a circular manner away from either side of the face so that the shape viewed by an on-coming vehicle is a partial cylindrical, spherical, elliptical or ovoid shape. The (or a) rounded portion of the face side(s) may extend approximately 90 degrees to one or both sides and project at least two channel widths beyond a channel side.

Face sides like this may be useful to widen the impact device face that a vehicle may strike and thereafter cause sliding movement. Rounded sides may be useful to assist with receiving and redirecting an impact force along the longitudinal length of the wire rope barrier.

Face Opening

In one embodiment, the face comprises an opening and wherein the opening provides a passage leading to the elongated channel through which wire rope may be threaded. the impact device may have at least one opening in the face, the opening configured to provide a snug fit for wire ropes passing therethrough. In the context of this specification, the term ‘snug’ refers to the wire ropes having little tolerance for wire movement in a lateral direction through the opening. In one embodiment, the face opening may be rectangular in shape. The face opening may be approximately the width of 1-2 wire diameters and a height approximately equivalent to 3, or 4, or 5 wire diameters. A narrower face opening may be advantageous to restrict the area through which wire ropes may slide and gather together the wire ropes about the opening. This gathering action may increase friction between the impact device and the wire ropes.

The face opening and particularly where wire ropes and the opening walls impinge on each other, may be shaped to encourage sliding movement in the event of an impact on the impact device. Shaping may include smoothing of edges, shaping of edges and the like to encourage movement and minimise risk of snagging between the wire ropes and impact device. Friction increasing or decreasing features may also be used or applied about the opening walls to increase or decrease friction and resistance to sliding about the opening.

The opening in the face may in one embodiment be located about or near the base of the face. The base may be the lower side of the face being located closest to ground level. Other locations may be used however, a lower position may be useful to direct wire ropes under or away from the vehicle front in the event of a vehicle impact, the impact device face being positioned at a height that generally coincides or extends above the vehicle front, the face opening being at a low point generally beneath or about the vehicle front.

Wire Rope Movement about the Face

As an alternative to wire rope movement through a face opening, the wire rope may be directed to move about the face of the impact device. For example, wire ropes may be directed below, along a side or sides of the face or above the face. Directing may come from the channel cavity or opening assuming a channel is used to house the wire rope as part of the impact device. The wire rope may impinge on the base, side(s) or top of the face to create a friction interface between the face and wire ropes during sliding movement. The face may further comprise an indentation or shaped interface on the face base, side(s) or top that act to direct or retain the wire rope(s) relative to the face.

Guide Member

As noted above, the impact device may comprise a guide member with the function of receiving and retaining at least one barrier wire rope about or therein.

In one embodiment, the guide member may take the form of a channel shape or alternatively, in an alternative embodiment, the guide member may take the form of a pair of brackets. Common to either embodiment is that the channel or pair of brackets receive and retain therein at least one barrier wire rope. Also common to both embodiments and possible other guide members shapes is that the guide member has an elongated form so that a section of wire rope may be received and retained therein. Elongated refers to the length of the guide member that runs approximately parallel to the wire rope or ropes being at least 5, or 10, or 15, or 20 times longer than the height or width of the guide member.

Hereafter, the terms ‘guide member’ and ‘channel’ and grammatical variations thereof are used interchangeably and reference to a guide member does not exclude a channel and reference to a channel does not exclude the use of other forms of guide member such as pairs of brackets having a similar function.

The elongated channel may comprise various shapes. Reference is made for ease of reading to a U-shape cross-section channel shape however, this should not be seen as limiting as other wire rope receiving and capture shapes may be used. By way of example, the channel may be a tube (circular or semi-circular). The channel may have a variety of different cross-section forms e.g. U-shape, O-shape, C-shape etc.

Elongated Channel Length

The elongated channel may have a length that is at least 25% of the length of the terminal end of wire rope between a final post in a wire rope barrier section and a wire rope anchor point. There may be an optimum elongated channel length. If the length is too short, a vehicle impact on the impact device may cause the impact device to not slide straight along the wire ropes and snag or twist. If the channel is too long, the impact device becomes impractical to install or requires extended length terminal ends. In the inventor's experience, the minimum length may be from approximately 300, or 400, or 500, or 600, or 700, or 800, or 900, or 1000 mm. The maximum length may be from approximately 2000, or 2500, or 3000, or 3500, or 4000 mm.

Elongated Channel Cavity and Opening

The elongated channel may have an internal cavity defined by a base, side walls and optionally, lips defining an opening between the lips. The cavity and opening if present may be located longitudinally along the channel length. The cavity and opening if present may run parallel to the channel longitudinal axis. The cavity and opening if present may be continuous along the channel length.

In one embodiment, the channel cavity opening if present may be located about or on the top of the impact device. The ‘top’ in this context refers to a side located away from the ground surface on which the impact device, terminal end or barrier is mounted.

The opening may be sized in width so as to receive at least one wire rope therethrough. The cavity width and/or height may be sized to receive two to four wire ropes therein.

In one embodiment, the channel cavity may have a width approximately 1, or 2, or 3 times a wire rope diameter and a height approximately 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10 times a wire rope diameter.

All wire rope(s) used to form the wire rope barrier may be received and captured within the channel cavity.

In one embodiment, the channel is manufactured from a substantially rigid material. The compression strength of the channel material may be greater than the compression strength of the wire rope(s). The channel strength may be sufficient that no or minimal plastic deformation occurs to the channel on impact by a vehicle and/or, on subsequent sliding advancement of the impact device downstream along the wire rope(s).

A channel downstream end may have a leading edge or opening to encourage sliding and re-directing of wire ropes. The leading edge may for example be smoothed or shaped to urge gathering of wire rope(s) and smooth transfer of wire ropes during movement into the channel.

Channel Houses the Wire Ropes

The channel cavity as noted above may house and retain together the wire rope(s) therein. To alter the sliding and friction characteristics of the impact device, the channel cavity shape and size may be altered to increase or decrease the snugness of the fit and interference between the wire rope(s) and channel cavity walls. The term ‘housed’ refers to the wire rope(s) being located inside or surrounded by the channel walls and floor along the region about which the channel length follows the wire rope path.

In one embodiment, all wire rope(s) used to form the wire rope barrier are received and captured within the channel.

Channel and Face Link Together

In one embodiment the channel and face of the impact device are one integral part. In an alternative embodiment, the channel and face of the impact device are two or more separate parts linked together. Linking may be via welding and/or use of fasteners. Linking together may occur prior to the impact device being fitted to wire ropes or may be completed in-situ during installation of the impact device to wire ropes. Linking may occur when a collision occurs e.g. friction welding during movement or movement causing mechanical coupling of a linkage etc.

No Fasteners to Link Impact Device to Wire Ropes

No fasteners may be needed in the above embodiments to directly join or link the impact device and the wire ropes together. As noted above, the device and wire rope(s) slidingly engage together and are held together before and during an impact via tension/friction of the ropes acting on the channel walls or a part thereof.

Channel Opening Obstruction

In embodiments using a channel with an opening that the wire rope(s) fit through, the opening may include at least one obstruction member to obstruct wire rope exit from the channel.

In one embodiment, the obstruction member or members may take the form of a bolt or bolts fastened across the channel opening typically in a spaced apart relationship with the bolt longitudinal axis orthogonal to the channel opening longitudinal axis.

Obstruction members in this embodiment may not directly impinge on or touch the wire rope(s) when the impact device is fitted about the wire ropes but may impinge on or touch or strike the wire ropes in the event of an impact and movement of the impact device along the wire rope(s). The obstruction members may act to lock the wire rope(s) within the channel during sliding movement.

Obstruction members such as bolts described may also be useful to help provide additional strength about the channel opening and prevent elastic or plastic deformation of the opening or channel as a whole causing the opening to widen and release the wire rope(s) therein in an impact.

Impact Device Base

The impact device may comprise a base. The base may be configured as legs, rails or at least one shaped projection. The base or a part thereof may contact the ground beneath the impact device post install and/or during an impact and subsequent sliding movement. The base may contact the ground even if only temporarily during an impact. The base may not contact the ground post install but may act to direct or deflect the impact device above the ground during an impact.

Use of a base may be helpful to ensure the impact device remains at a preferred height particularly as the impact device advances along the wire ropes in an impact. A drop-in impact device height relative to the ground could result in the device sliding under the vehicle to be slowed and/or directed leading to ramping or incomplete slowing.

Tuning the Extent of Energy Absorbing

The extent of energy absorbing caused by the impact device may be varied. The basic function of the impact device may be to absorb at least some degree of impact through friction of movement along the wire rope(s) by the impact device. This degree of friction may be altered by features which affect the frictional engagement between the impact device and the wire rope(s). For example, projections may be used along the inside of the cable channel which, when the device is clamped about a wire rope, may define a tortuous path for the cable through the impact device thereby increasing the degree of friction.

Retrofit or New Manufacture

The impact device described may be designed and fitted to a newly installed wire rope barrier. Alternatively, the nature of the impact device design is such that it may be fitted to already existing wire rope barrier terminal ends. This versatility and in particular, the ability to retrofit the impact device on existing barriers is a considerable advantage as it reduces the cost of improving barrier safety and avoids comprehensive redesign and/or reinstallation. The impact device described by virtue of its design also may be fitted to a variety of different wire rope barriers types and configurations. Again, this increases the value and versatility of the impact device described.

Method of Assembly

The impact device described herein may be fitted to a wire rope barrier by inserting or threading the wire ropes (typically 2-4 wire ropes) that form the length of need (LON) of a wire rope barrier into the downstream end of the device (the channel opening) and are pulled through to the upstream end of the channel (vehicle impacted end) and through the face opening. The wire ropes extending from the opening are then anchored to the ground via art methods such as concrete or soil foundations.

Advantages

As may be appreciated from the above, it may be useful to provide a wire rope terminal end with a device that helps to reduce/avoid driver injury. Reduction may be through enhanced barrier collapse dynamics in the event of an impact to the terminal end.

Amendment of existing terminal ends with minimal cost may be useful too especially given the considerable infrastructure already in place and the considerable value and importance placed on increased driving safety.

A further advantage may be to provide a design that allows for shorter terminal ends (at least 10% smaller length) and therefore reduce the barrier footprint and potentially redirect errant vehicles at a point closer to the terminal end section of a wire rope barrier.

The design encapsulates all cables from the outset thereby reducing the risk of snagging and sudden deceleration of energy absorbing failure.

The embodiments described above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relate, such known equivalents are deemed to be incorporated herein as if individually set forth.

EXAMPLES

The above impact device, a wire rope barrier terminal end, and a wire rope barrier are now described by reference to specific examples.

Example 1

In this example the impact device itself is described with reference to FIGS. 1 to 6 .

The impact device (arrow 1) comprises a face 2, an opening 3 in the face 2 with a passage through the opening 3 leading to an elongated channel 4. The impact device 1 is configured to slidingly engage, at least one barrier wire rope in the channel 4 and through the opening 3 (shown below in Example 2 and FIGS. 7, 11 and 12 ). The direction of sliding is shown by arrow F in the Figures traveling from an upstream end 6 to a downstream end 7.

The face 3 of the impact device 1 may have a generally flat planar face 3 like the illustrated rectangular face 3. The face may comprise projections (see 100 in FIG. 2 ) or other face features on a vehicle impact side that serve to engage with an errant vehicle or part thereof (e.g. the vehicle bumper, wheel, bodywork and so on) during an impact event.

The impact device 1 face 3 may have reinforcing flanges, fins, or struts 16 extending from the face 3 to a point located along the channel 4.

The face 3 may comprise an impact plate 17 on the face 3 for engaging an errant vehicle (shown later in Example 4). The impact plate 17 may be sufficiently strong and/or hard to not deform when initially impacted. Alternatively, the impact plate 17 may be designed to, at least to some extent, deform when struck and in doing some absorb kinetic energy from the impact.

The face 3 of the impact device 1 may optionally include sides 18 configured to extend the impact region on the impact device 1. These are not essential. An example of semi-circular sides 18 is shown in FIG. 7 .

The opening 3 in the face 2 may be configured to provide a snug fit for wire ropes passing therethrough, the wire ropes having little tolerance for wire movement in a lateral direction through the opening. As shown in the Figures, the face 2 opening 3 may be rectangular in shape.

The face 2 opening 3 and particularly where wire ropes and the opening 3 edges impinge on each other may be shaped to encourage (or discourage) sliding movement in the event of an impact on the impact device.

The face 2 opening 3 may be located as shown in the Figures about or near the base of the impact plate 17. The base as shown in the lower side of the face 2 being located closest to ground 12.

The elongated channel 4 may comprise various shapes. The figures show a U-shape cross-section channel 4 shape however, other wire rope receiving and capture shapes may be used.

The elongated channel 4 has cavity 21 defined by a base 23, side walls 22 and optionally, lips 24 defining an opening between the lips 24 best seen in FIG. 12 . The cavity 21 and lip 24 opening are located longitudinally along the channel 4 length and the lip 24 opening runs parallel and continuous along the channel 4 longitudinal axis. The channel 4 has a width 26.

The channel 4 cavity 21 is located about the top 25 of the impact device 1.

The cavity 21 opening is sized in width so as to receive two to four wire ropes therethrough.

In the Figures, the channel 4 is manufactured from a substantially rigid material.

The channel 4 downstream 7 end may have a leading edge 27 to encourage sliding and re-directing of wire ropes.

The channel 4 cavity 21 houses and retains together the wire rope(s) therein. To alter the sliding and friction characteristics of the impact device 1, the channel 4 cavity 21 shape and size may be altered to increase or decrease the snugness of the fit and interference between the wire rope(s) and channel 4 cavity 21 walls.

The channel 4 includes a series of spaced apart bolts 28 to obstruct wire rope exit from the channel 4 once fitted. The bolts 28 are fastened across the channel 4 opening with the bolt 28 longitudinal axis orthogonal to the channel 4 opening 5 longitudinal axis. The bolts 28 not directly impinge on or touch the wire rope(s) when the impact device 1 is fitted about the wire ropes but may impinge on or touch or strike the wire ropes in the event of an impact and movement of the impact device along the wire rope(s).

In the example shown and best seen in FIG. 2 , the face 2 may have directional strength during impacts depending on whether the impact is in a normal sliding forward direction F and the vehicle impacts directly on the face, or in the reverse direction, arrow F_(R). In the forward direction F, the face 2 corners 110 may be strong or strengthened and therefore may resist buckling or bending of the face 2. This may allow a vehicle (not shown) to be held in contact with the face 2 during the period of the impact event. In the event of a reverse direction F_(R) impact directly behind the face 2, the face 2 and connecting members 110 may comprise relatively weak areas 120, these weak areas 120 bending or deforming thereby reducing the likelihood that the vehicle will rebound or be redirected off the device 1 and back into the road/traffic.

In a further embodiment, if a vehicle impacts the strut 16, the strut 16 may be designed to be relatively weak so that the strut(s) 16 bend or deform. This approach may also reduce the likelihood that the vehicle is redirected back into the traffic flow.

Example 2

An example of installed impact device 1 is now described with particular reference to FIGS. 7, 11 and 12 .

In this case, a wire rope barrier 50 (best seen in FIGS. 13-21 being the section of barrier prior to the final post 10 and terminal end 9 is shown comprising wire ropes 8, barrier 50 terminal ends 9 and an impact device 1 installed at a terminal end 9. The barrier 50 comprises three or four wire ropes 8 in the drawings, the barrier 50 section of the wire ropes 8 located generally parallel to a roadway (not shown) and held above the ground 12 surface via a series of posts 10.

The terminal end 9 comprises three or four wire ropes 8 as shown in the Figures, a post 10 about the transition from barrier 50 section to terminal end 9 and anchor points 11 for the wire ropes 8.

Mounted on the terminal end 9 is the impact device 1 described in Example 1. In this case, the wire ropes 8 are shown threaded through the opening 3 in the face 2 with a passage through the opening 3 leading to the channel 4.

The terminal end 9 commences about a final post 10, the wire ropes 8 of the barrier 50 sloping from a first vertical height on the downstream 7 side of the terminal end 9 equivalent to the rest of the barrier 50 height to a second vertical height on the upstream side 6 of the terminal end 9 below the first vertical height, the second vertical height typically proximate the surface of the ground 12.

The impact device 1 described may be fitted to a wire rope 8 barrier 50 terminal end 9 by inserting or threading the wire ropes 8 (typically two to four wire ropes 8) that form the length of need (LON) of a wire rope 8 barrier 50 into the downstream 7 end of the device 1 (the channel 4 end) and are pulled through to the upstream end of the channel 4 (vehicle impacted end) and through the face 2 opening 3. The wire ropes 8 extending from the opening 3 are then anchored 11 to the ground 12.

The impact device 1 described may be designed and fitted to a newly installed wire rope barrier 50 or fitted to already existing wire rope barrier 50 terminal ends 9. This versatility and in particular, the ability to retrofit the impact device 1 on existing barriers 50 is a considerable advantage as it reduces the cost of improving barrier 50 safety but avoiding comprehensive redesign.

Example 3

Selected alternate variations of the above design are now described with reference to FIGS. 8, 9 and 10 .

As noted above, the impact device absorbs energy associated with an impact in turn at least to some extent, decelerating a vehicle and, at least to some extent, controlling the direction of the impact force and if needed, re-directing an impact force imposed on the impact device by an errant vehicle. The way that energy is absorbed may be due to friction caused by the wire ropes 8 moving through the impact device opening and channel and interfering with sliding movement of the impact device 1. The degree of friction imposed (and hence degree of energy absorbing) may be varied by amendment to the impact device 1 design. For example, the path of movement of one or more wire ropes through the impact device may be straight as shown in FIGS. 7, 11 and 12 or curved/tortuous as shown in FIG. 8 , in this example using constrictor components 14 to force the wire ropes 8 to move in curved paths. A straight path may present a lower degree of interference than a curved or tortuous path and hence a varied degree of friction resulting.

The presence of other obstructions 14 may be used as well. FIG. 9 illustrates how a crimp type fixing 30 may be used about the wire rope 8 circumference that interferes with the direction of travel of the impact device 1 (in FIG. 9 shown as a plate). When the narrower aperture of an impact device 1 plate strikes the crimp fixing 30 which has a wider diameter, the crimp 30 and plate 1 impact may cause plastic deformation of the crimp 30 or plate 1 thereby absorbing more energy and/or slowing sliding movement of the impact device 1.

FIGS. 7, 10 and 13-21 show another variation being the base 40 of the impact device 1. The base 40 may take the form of legs (FIGS. 13-21 ), rails or at least one shaped projection (FIGS. 7 and 10 ). The base 40 or a part thereof may contact the ground 12 beneath the impact device 1 post install. The base 40 may contact the ground 12 even if only temporarily during an impact. Use of a base 40 may be helpful to ensure the impact device 1 remains at a preferred height above ground, particularly as the impact device 1 advances along the wire ropes 8 in an impact further described below in Example 4.

Example 4

The behaviour of the impact device 1, terminal end 9 and barrier 50 are now described with reference to FIGS. 13-21 .

As noted above, the impact device 1 absorbs energy associated with an impact, in turn at least to some extent, decelerating a vehicle 13 and, at least to some extent, controlling the direction of the impact force and if needed, re-directing an impact force imposed on the impact device by an errant vehicle 13.

FIGS. 13 to 21 illustrate step by step the movement and actions that may take place in the event of an impact by a vehicle 13 on the impact device 1.

Referring first to FIG. 13 , the errant vehicle 13 is shown immediately prior to impact on the impact device 1. The vehicle 13 is heading in a direction roughly parallel to the barrier 50 although as noted above, the vehicle 13 may not need to be moving in a direction completely parallel and may be at an angle to the barrier 50 longitudinal axis. As shown in FIG. 13 , the barrier section 50 comprises three wire ropes 8 with spaced apart posts 10 and a terminal end 9. On the terminal end 9 is an impact device 1 comprising a face 2 and channel 4. The impact device 1 has a base 40.

FIGS. 14 to 21 show how the impact device 1, once impacted by an errant vehicle 13 is pushed via sliding action downstream along the wire rope(s) 8 and the impact device 1 as it moves, deforms the barrier 50 posts 10, clearing the posts 10 out of the way of the vehicle 13 during sliding movement. The impact device 1 also removes the cables 8 from their post 10 connection at the same time as knocking over the posts 10. As shown in FIGS. 13-21 , it can be seen how the impact device 1 gathers and directs the wire ropes 8 during sliding travel.

Example 5

In this example an alternative embodiment is illustrated with reference to FIG. 22 showing an embodiment where the face does not have an opening. As shown in FIG. 22 , the assembly comprises a wire rope barrier portion on the right hand side of FIG. 22 comprising wire ropes 8 and posts 10 located above the ground 12. At the terminal end, shown to the left of FIG. 22 , an impact device 1 is shown comprising a face 2 and guide member 4. The wire ropes are received and retained within the guide member 4 along the elongated length of the guide member 4 however, towards the face 2 end of the impact device 1, the guide member 4 has a void 200 that the gathered cables 8 may exit. The cables 8 exit the void 200 as shown and attach to the ground 12 at an anchor point. As shown, the cables 8 extend under the face 2 and not via a hole in the face 2 itself. In the event of an impact on the face 2, the impact device slides along the cables 8 as per earlier embodiments, cables 8 exiting the guide member 4 via the void 200.

Optionally, the guide element 4 may also comprise a lip 500. The lip 500 may be located about the void 200 in the guide element 4 and the lip 500 may act to direct wire rope 8 from the guide member 4. The lip 500 may take a variety of forms and shapes such as a flap or tongue shape and may extend beyond the void 200 at least somewhat and angled down slightly from the void 200 opening. The extent of angle down may be commensurate with the natural direction of angel of wire rope 8 as it extends from the void 200 to the ground 12 anchor.

Example 6

In this example, alternative guide member embodiments are illustrated. Referring to FIGS. 23 and 24 , the impact device 1 is shown located at a terminal end of the wire rope barrier as per earlier embodiments. The impact device 1 comprises a face 2 and in this example a pair of brackets 300 that receive and retain the wire ropes 8. In FIGS. 23 and 24 the brackets 300 comprise steel sections and a fastener that links the sections together about the wire ropes 8. In this embodiment, the impact device 1 still slidingly engages the wire ropes 8 and moves along the wire ropes 8 in the event of an impact pushing the posts 10 out of the way as movement occurs.

FIGS. 25 and 26 illustrate a similar bracket approach, in this example having the body of the guide element located below the wire ropes and U-shaped brackets 300 extending up and over the wire ropes 8 to retain the guide member to the wire ropes 8.

Further, as best seen in FIG. 26 , the wire ropes 8 extend about the sides of the face 2, in this example, two wire ropes 8 extend on each side of the face 2 about a mid-point in the face 2 height. This example further illustrates how the wire ropes 8 may extend through an opening in the face, below the face or as shown here about the face 2 sides.

Further, note that the brackets 300 in the embodiments shown in FIGS. 23-26 may comprise features to increase or decrease the sliding friction force. For example, the bracket 300 shape, internal finish and/or extensions or members (not shown) may be altered to change the sliding dynamics of the impact device 1. For example, the brackets 300 may be crimped against the wire ropes 8 during installation, the brackets 300 may have a high friction internal surface that interferes with the wire ropes 8 or the brackets 300 may comprise a shape that interferes with wire rope 8 sliding movement, these factors alone or collectively increasing the friction force during sliding and therefore altering the dynamics of the impact device 1 when struck by an errant vehicle. Opposite approaches to the above such as have loose or no gripping by the brackets 300 to the wire ropes 8, low friction surfaces and clear bracket 300 shapes to reduce the degree of friction and therefore allow for more sliding movement.

Aspects of the impact device, a wire rope barrier terminal end, and a wire rope barrier have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein. 

1. An impact device comprising: a contact element configured to contact and optionally engage an errant vehicle in a collision event, a guide member configured to receive and retain at least one wire rope from a wire rope barrier or wire rope barrier terminal end about or therein, and, in the event of an impact, the impact device slidingly engages the at least one wire rope about or therein the guide member and wherein the at least one wire rope is directed about or through the contact element during sliding of the impact device along the at least one barrier wire rope.
 2. The impact device as claimed in claim 1 wherein the guide member is elongated and 5-20 times longer than the guide member height or width.
 3. The impact device as claimed in claim 1 wherein the guide member is configured to have a length that takes up 25% or more of the length of need (LON) of a wire rope barrier terminal end.
 4. The impact device as claimed in claim 1, wherein the impact device is configured to gather and direct movement of all of wire ropes of the wire rope barrier during sliding travel of the impact device.
 5. The impact device as claimed in claim 1, wherein the impact device is configured to be fitted to the wire rope with friction and without need for fasteners, with the guide member holding the impact device in place relative to the wire rope.
 6. The impact device as claimed in claim 1 wherein the contact element comprises an impact plate with projections on the contact element configured to engage an errant vehicle impacting the impact device.
 7. The impact device as claimed in claim 1, wherein the contact element includes rounded sides extending from the contact element configured to extend the impact region on the impact device contact element.
 8. The impact device as claimed in claim 1, wherein the contact element has weakened areas that break or deform when a reverse impact occurs.
 9. The impact device as claimed in claim 1, wherein the contact element is configured to mechanically deform in the event of an impact.
 10. The impact device as claimed in claim 1, wherein the contact element comprises an opening and wherein the opening provides a passage leading to the guide member through which wire rope is threaded.
 11. The impact device as claimed in claim 1, wherein the at least one wire rope is directed under or over the contact element.
 12. The impact device as claimed in claim 1, wherein the guide member is an elongated channel or pair of brackets configured to gather and direct movement of wire rope therein during sliding travel of the impact device.
 13. The impact device as claimed in claim 12 wherein the elongated channel or pair of brackets include obstruction members to obstruct wire rope exit from the channel or pair of brackets and, wherein the obstruction members do not impinge on the wire rope in the guide member.
 14. The impact device as claimed in claim 1, wherein the guide member internal shape is varied to alter the sliding friction on the wire ropes.
 15. The impact device as claimed in claim 1 wherein the impact device comprises a base configured as legs, rails or at least one shaped projection, the base or a part thereof contacting-the ground beneath the impact device post install and/or during an impact and subsequent sliding movement.
 16. A terminal end of a wire rope barrier comprising: at least one wire rope extending from the wire rope barrier to the terminal end; at least one post and at least one anchor point for the at least one wire rope; the terminal end configured to gather and direct the at least one wire rope from the wire rope barrier position with the wire rope elevated above a ground surface to an anchored position about or on ground surface; and an impact device as claimed in claim
 1. 17. The terminal end as claimed in claim 16 wherein the terminal end of the wire rope barrier comprises 3 to 4 wire ropes.
 18. The terminal end as claimed in claim 17 wherein the wire ropes flare about a horizontal plane from the contact element to the ground anchor points.
 19. A wire rope barrier comprising wire rope, terminal ends and at least one impact device, wherein: the wire rope barrier comprises at least one wire rope located generally parallel to a roadway and held above road surface via a series of posts; terminal ends of at least one wire rope, at least one post and at least one anchor point for the at least one wire rope, the terminal ends being configured to gather and direct at least one wire rope from a barrier position with the wire rope elevated above a ground surface to an anchored position about or on the ground surface; and mounted on or about one or both terminal ends, the at least one impact device as claimed in claim 1; and wherein, once impacted, the impact device is configured to be pushed, via sliding action, downstream along the wire rope of the terminal end and wire rope barrier itself, the impact device gathering and directing movement of the wire rope barrier wire rope during sliding travel of the impact device.
 20. The wire rope barrier as claimed in claim 19 wherein, as the impact device slides, the impact device is configured to deform wire rope barrier posts, clearing the posts out of the way of the impact device during sliding movement.
 21. The wire rope barrier as claimed in claim 19 wherein, as the impact device slides, the impact device removes the wire rope barrier wire cables from their post connection.
 22. The wire rope barrier as claimed in claim 19 wherein the terminal end of the wire rope barrier comprises 3 to 4 wire ropes.
 23. A method of absorbing and directing the energy associated with an impact on or about a wire rope barrier terminal end by a vehicle, comprising the steps of: providing a wire rope barrier as claimed in claim 19; and in the event of an impact by a vehicle to the wire rope barrier terminal end, the impact is at least partly received by the impact device and, on impact, the impact device slides along the at least one wire rope.
 24. The method as claimed in claim 23 wherein the action of sliding at least partly absorbs kinetic energy and at least to some extent, redirects the direction of impact force to coincide with the direction of movement of the impact device along the wire rope.
 25. The method as claimed in 23 wherein the action of the impact device sliding acts to knock over posts as the impact device advances along the wire rope. 